This invention concerns improvements in or relating to ventilators for controlling air flow and in particular, though not exclusively, for controlling air flow through an air path formed in a frame of a door or window.
Ventilators are known in which a flap is pivotal to open and close a ventilation opening to control air flow through an air path formed in door or window frames. The design and construction of such ventilators is often complex requiring manufacture and assembly of several parts which increases the cost.
In use, the ventilator is mounted on the inner face of the frame and an exterior hood is often mounted on the outer face of the frame to prevent water penetration. It is usual to fit a fine mesh or the like within the hood to exclude insects but this reduces the cross-sectional area of the ventilation opening so that the ventilation opening has to be made larger than required to obtain the necessary air flow.
The present invention has been made from a consideration of the above problems.